Basil of Caesarea (330–379 AD), known as Basil the Great, was a bishop and influential theologian who supported the Nicene Creed. He was one of the Cappadocian Fathers, along with his brother Gregory of Nyssa and friend Gregory of Nazianzus.
Basil made significant contributions to Christian monasticism and liturgy. His writings on the Holy Spirit explore how souls illuminated by the Spirit become spiritual themselves and send forth grace to others, becoming like God through divine participation.
He established guidelines for monastic life that influenced both Eastern and Western monasticism, and his liturgy is still used in Eastern Orthodox churches. Basil’s theology of deification emphasizes the transformative work of the Holy Spirit in making humans partakers of the divine nature.